1. Field of the Invention
This invention relates games and amusement devices, and specifically to three-dimensional puzzles with sliding interlocking pieces, and more particularly to puzzles having pieces that require sequential movement of the pieces during assembly and disassembly.
2. Description of the Background Art
Interlocking solid puzzles of many types have existed and have been a source of enjoyment for many years. A major challenge in this field is in coming up with new puzzles that are appealing in ways that will capture the interest of consumers.
Prior art on puzzles can be found in "Puzzles Old & New", by J. Slocum & J. Botermans, copyright 1986, published by Plenary Publications Int., The Netherlands. Page 62 through 85 in the section on interlocking solid puzzles provides a good characterization of interlocking solid puzzle. This information can also be used to distinguish them from other types of puzzles such a jigsaw puzzles. This section covers the well known 6 piece burr puzzles. In the ideal versions of these puzzles the number of notches applied to the bars are such that no empty spaces exist in the assembled puzzle. One of the problems with these ideal versions is that a piece can always be removed from the assembled puzzle without requiring shifts of other pieces. This makes these puzzles less challenging to disassemble. More challenging burr puzzles are covered that require one or more shifts before an initial piece can be removed, however, this requires additional notches and results in empty spaces in the assembled puzzle. This is a drawback that causes the puzzle to be less aesthetically and mathematically pleasing. Another problem with the burr puzzle is the difficulty in using an existing puzzle to create a more challenging one with more shifts required for disassembly. For example just the smallest change in the position or shape of a notch will often ruin the puzzle, such that it can no longer be assembled into the burr shape. While the 6 piece burr puzzles have a visually appealing assembled form, a partially assembled puzzle seldom results in a interesting or visually stimulating arrangement. Besides the assembled form of the burr puzzle, creative arrangements of pieces that are visually stimulating or interesting are difficult to find.
One of the other types of interlocking solid puzzles covered within pages 62-85 of "Puzzles Old & New" are those with complex geometric forms. These include a dodecahedron shaped puzzle on page 62, a hexagonal puzzle on page 69, the puzzles called Lightning, Grand Prix, and Kubion on page 76, the puzzles called Cuckoo Nest, and Locked Nest on page 82, the three polyhedral puzzles on page 84, and the puzzle called Jupiter on page 85. While these puzzles can be considered works of art, in order to make these puzzles challenging, a large number of pieces is often required. A problem here is that puzzles with a large number of pieces are less popular as such puzzles are difficult for the average puzzle enthusiast to assemble. Although they have a very visually appealing assembled form, these geometric form puzzles are often easy to disassemble. Many do not require shifts or other movement of a piece before an initial piece or pieces can be removed from the assembled puzzle. Many of these types of puzzles are not stable in assembled form, or in many of the stages of assembly of the puzzle. The problem with this instability is that the puzzle can easily fall apart unless carefully supported, such as being held together by hand.
Prior art on interlocking solid puzzles is also covered at the Puzzle World web site on the Internet at address "http://www.johnrausch.com/PuzzleWorld/index.html". This site contains an on-line version of the book "The Puzzling World of Polyhedral Dissections," by Stewart Coffin. Chapter 4 of this on-line book covers Interlocking Block Puzzles that have the assembled form of a cube. This chapter discusses the difficulty in designing puzzles up to size-five. A size-four puzzle called the Convolution puzzle is presented that illustrates this difficulty. This shows that designers often have to revert to deformities to the basic cubic structures in order to create interesting cube puzzles of this size.
Another related type of interlocking solid puzzle is one that incorporates a maze while still being an assembly and disassembly puzzle. An example is U.S. Pat. No. 4,357,016 (1982) to Allison. This puzzle, and others of its type, have the disadvantage that piece movements are restricted to that along a defined surface within the puzzle. This surface is often planar, but can include other smooth surfaces such as that of a cylinder as proposed by Allison. This surface is often defined by a single piece frame member, but can use a frame formed by multiple members. Contact, between the frame and other pieces, is used to maintain the pieces in assembled form. An example is in the patent by Allison which includes a version where the surface is that of a cylinder defined by the inner surface of a single cylinder member, and another version where the surface is that of a cylinder defined by the surface of a plurality of stacked cylindrical bands. Another disadvantage of this type of puzzle is that a frame is required to maintain the pieces in assembled form.